Abstract
Biological diversity in the marine and coastal environment is declining globally. Several layers of governance intertwine in the regulation of biodiversity with multiple strains of policy developments taking place at the international, national and subnational levels. In particular, the subnational level of governance has become crucial in the implementation of biodiversity protection. The article aims at better understanding how governance mechanisms in defence of biodiversity can be developed and implemented at the subnational level and what obstacles they may face. For this purpose, the article relies on a single-case study: it analyses biodiversity policy in France and explains its subnational implementation in Reunion. Major achievements and impediments are also discussed for policy tools adopted for the protection of areas and species. The study reveals important bureaucratic, political and societal pressures that can affect subnational implementation together with the availability of material and immaterial resources. The article concludes with policy recommendations that are specific to Reunion but concern aspects common to other Outermost Regions of the European Union: centre-local coordination, regional strategy, public engagement and transnational collaboration.